<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		 <script>
		        var arr = [1, 1, 3, 8, 7, 3, 2, 5, 2, 1, 4, 3, 9, 3, 6, 9, 10, 8, 3, 8];
		        var arr1 = [];
		        for (var i = 0; i < arr.length; i++) {
		            if (arr1.indexOf(arr[i]) < 0) {
		                arr1.push(arr[i]);
		            }
		
		
		        }
		        alert(arr1);
		
		
		    </script>
	</body>
</html>
